Nitrous oxide (N2O) is used as an adjunct during general anaesthesia. Which of the following accurately describes its mechanism of analgesic action?

• A GABA-A receptor potentiation
• B Voltage-gated sodium channel blockade
• C Alpha-2 adrenoceptor agonism
• D NMDA receptor antagonism and endogenous opioid release ✓

Explanation

Nitrous oxide produces analgesia primarily by antagonizing NMDA (N-methyl-D-aspartate) receptors, thereby blocking excitatory glutamate transmission, and by stimulating release of endogenous opioid peptides. Its hypnotic effects involve GABA-A potentiation and NMDA inhibition together. This dual mechanism distinguishes N2O from other volatile agents.

Reference: Morgan & Mikhail's Clinical Anesthesiology, 6th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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